Organocatalytic Transannular Approach to Stereodefined Bicyclo[3.1.0]hexanes

J Org Chem. 2018 Apr 6;83(7):4180-4189. doi: 10.1021/acs.joc.8b00165. Epub 2018 Mar 19.

Abstract

A diastereodivergent approach to highly substituted bicyclo[3.1.0]hexanes has been developed through a transannular alkylation reaction that builds up the bicyclic core employing asymmetric organocatalysis as the tool for the installation of all stereocenters. On one hand, a Michael/Michael cascade process between enals and 4-alkenyl sulfamidate imines under the iminium/enamine activation manifold provides an oxathiazole-2,2-dioxide-fused cyclohexane adduct that, after isolation, is subsequently engaged in a transannular alkylation/hydrolysis through enamine activation by the use of a primary amine. On the other hand, the corresponding C-2 epimers are directly obtained from the same starting materials in a single operation through a cascade Michael/Michael/transannular alkylation/hydrolysis sequence through sequential iminium/enamine/enamine combination of aminocatalytic activation manifolds.

Publication types

  • Research Support, Non-U.S. Gov't